DE102013219989A1 - Method for producing a cast component with an insert - Google Patents

Abstract

The invention relates to a method for producing a cast component (6) with an insert (1), comprising the following steps: a) providing an insert (1) with an insert body (2) having a jacket surface (3), b) coating the insert Cladding surface (3) with an adapter layer (4) made of silicon oxide, c) arranging the insert part (1) in a casting mold, d) positive encasing the insert part and the adapter layer with an aluminum alloy (7) for producing the casting, wherein the aluminum alloy (7 ) has a magnesium content of at least 0.3% by weight, preferably at least 0.5% by weight.

Description

The invention relates to a method for producing a cast component and a cylinder liner and a cylinder block containing such a cylinder liner for an internal combustion engine. Furthermore, the invention relates to a piston ring carrier and such a piston ring carrier containing piston for an internal combustion engine.

Cylinder blocks of modern internal combustion engines are usually produced in a casting process. Since the material used for the cylinder block - usually aluminum or iron, but also suitable magnesium-aluminum composite materials - which is not required for a friction and thus possible wear-free movement of a piston in the cylinder required tribological requirements can not be met in the cylinders so-called cylinder liners used. These have the required tribological properties and thus ensure a largely wear-free long-term operation of the piston in the cylinder block; often such cylinder liners are provided with a roughened, grooved or machined in a similar manner lateral surface. Alternatively, the prior art also teaches the application of an aluminum spray layer on the lateral surface of the cylinder liner. In both cases, the casting of the cylinder liner with an aluminum alloy, which is likewise known from the prior art, can produce a particularly positive connection of the cylinder liner with the cylinder block.

In an analogous manner, the production of pistons for such internal combustion engines is usually carried out by means of a casting process. To seal the piston against the cylinder block so-called piston rings - usually made of steel - used, which can be inserted into a provided on a lateral surface of the piston circumferential groove to produce said sealing effect. In order to reduce the tribological load of the piston whose piston material is usually made of a lightweight aluminum alloy, compared to the piston ring formed of a steel, so-called piston ring carriers are used in conventional pistons, which are encapsulated in a casting process with the actual piston. This has the consequence that no direct, in particular wear-critical interface piston-piston ring is more present; Rather, said piston ring carrier now acts as a mechanical "interface" between the piston ring and the actual piston, wherein the circumferential groove for receiving the piston ring is now provided on the piston ring carrier.

The US 4,273,835 describes the manufacture of a cylinder block with a cylinder liner inserted into the cylinder of the cylinder block. Between cylinder liner and cylinder block a silicone resin layer is provided for sealing a water jacket.

The JP 2010-156003 A describes the coating of a cast iron workpiece with an adapter layer containing carbon, manganese, silicon, sulfur and phosphorus. The adapter layer increases the adhesion of an aluminum alloy applied to the workpiece.

A particularly form-fitting connection between cylinder liner and cylinder block or between piston ring carrier and piston - hereinafter, the two components are each generalized as "insert" and "molded component" referred to - meanwhile results in the use of a so-called. Aluminum die-casting process for encapsulating the insert an aluminum alloy which, however, is increasingly dispensed with in favor of low pressure or gravity casting techniques, often for cost reasons, in the manufacture of modern internal combustion engines. By means of low-pressure or gravity casting techniques, however, the quality of the positive engagement of the insert with the cast component, which can be achieved using the aluminum die-casting method, can not be achieved by far.

However, a not properly pronounced positive connection between the insert and cylinder block usually leads to only a reduced thermal coupling of the insert to the molded component, which in turn can have unwanted, thermally induced mechanical stresses in the insert or in the cast component result.

The present invention therefore deals with the problem of providing an improved embodiment of a method for producing a cast component and for an insert, which no longer has the disadvantages mentioned above.

This problem is solved by the subject matter of the independent claims. Preferred embodiments are subject of the dependent claims.

The basic idea of the invention is accordingly to coat the outer surface of an insert in the course of the production process, namely by means of a layer of silicon oxide referred to below as an adapter layer. Said adapter layer leads during encapsulation with an aluminum alloy - in particular using the Initially presented aluminum die casting after their introduction into a suitable mold - to an improved wetting behavior of the aluminum alloy on the adapter layer. Corresponding experimental studies have shown, however, that this only applies in the case that the aluminum alloy is provided with a magnesium content of at least 0.3% by weight, preferably at least 0.5% by weight. As a result of the improved wetting properties of the aluminum alloy on the silicon oxide of the adapter layer, a particularly positive connection between cylinder liner and aluminum alloy, which completes the insert to the molded component, can be achieved.

A particularly positive connection results in the use of the adapter layer according to the invention not only in the so-called. Aluminum die-casting process, but also in the low-pressure or gravity casting. By means of the adapter layer, the quality of the positive connection of the insert with the cast component achievable with the use of the aluminum die-casting method can also be achieved by means of low-pressure or gravity casting techniques.

Particular advantages offered by the method presented here, especially when the insert is a cylinder liner and the cast component is a cylinder block for an internal combustion engine, or if the insert is a piston ring carrier and the molded component is a piston for an internal combustion engine.

• b1) Aufbringen eines Silikonharzes auf die Mantelfläche,
• b2) Aushärten des Silkonharzes zu Siliziumoxid durch Erhitzen des Einlegekörpers.

Preferably, step b) of the method according to the invention, according to which the lateral surface is coated with an adapter layer made of silicon oxide, can comprise the following two sub-steps b1) and b2):

• b1) applying a silicone resin to the lateral surface,
• b2) curing the silicone resin to silicon oxide by heating the insert body.

Silicone resin is commercially available in large quantities in liquid form and therefore inexpensive. In addition, it can be applied in a simple manner on the lateral surface of the cylinder liner, before it is used for casting in the cylinder block. The conversion of the organic silicone resin in silicon oxide is also very simple: For this purpose, it is sufficient to heat the coated silicone resin insert component - for example, to a temperature of 400 ° C or more - and cure in this way, the silicone resin to silica. The hardened silicon oxide can react with the magnesium contained in the aluminum alloy in the region of the interface to the aluminum alloy according to the reaction equation SiO ₂ + 2 Mg -> 2 MgO + Si, whereby the wetting of the surface can be decisively improved.

As particularly expedient it proves to dilute the silicone resin prior to application to the lateral surface according to step b1) of the method according to the invention with a solvent; In this way, a particularly uniform coverage of the lateral surface with silicone resin succeeds before the oxidation process.

Particularly good results in the curing of the silicone resin to silica and the associated hardening of the oxidized silicon after its heating can be achieved if the silicone resin has a layer thickness of 5 to 10 microns before curing to silica. In general, a small layer thickness promotes a rapid curing process, which can have an advantageous effect on the industrial production of the inserts in large quantities.

An alternative realization of the adapter layer of silicon oxide according to the invention offers the use of a solution of so-called water glass. The term "water glass" includes all water-soluble sodium, potassium and silicon silicates solidified from a melt. These have glassy, so amorphous material properties. After immersion in the water glass solution, the cylinder liner is cured as described above in connection with silicone resin by heating the insert, preferably to a temperature of 400 ° C or more. In this case, the adapter layer loses its water content, so that a substantially anhydrous, polymerized inorganic silicate is formed. Also according to this embodiment, the hardened silica in the region of the aluminum alloy interface according to the reaction equation SiO ₂ + 2 Mg -> 2 MgO + Si can react with the magnesium contained in the aluminum alloy, resulting in improved surface wetting.

Particularly expediently, the water glass comprises Na ₂ O ₃ Si, ie sodium silicate.

The invention also relates to a cylinder liner with a jacket surface having a lateral surface, wherein the lateral surface of the female body is coated with an adapter layer of silicon oxide. Such an adapter layer also expressly includes the above-described MgO or Si obtained by reaction with SiO ₂ with Mg in the transition region of the adapter layer to the aluminum alloy.

The invention further relates to a cylinder block with such a cylinder liner, as well with an aluminum alloy surrounding the adapter layer, which completes the cylinder liner to the cylinder block.

The invention further provides a piston ring carrier having a shell surface having a ring body, wherein the lateral surface of the ring body is coated with an adapter layer of silicon oxide.

The invention finally relates to a piston with such a piston ring carrier, as well as with an aluminum alloy surrounding the adapter layer, which completes the piston ring carrier to the piston.

Other important features and advantages of the invention will become apparent from the dependent claims, from the drawings and from the associated figure description with reference to the drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Preferred embodiments of the invention are illustrated in the drawings and will be described in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical components.

It show, each schematically

1 a silica coated cylinder liner prior to insertion into a mold for making a cylinder block,

2 a cylinder liner encased in a casting with an aluminum alloy, which forms a cylinder block together with the aluminum alloy,

3 an encircled with an aluminum alloy ring carrier, which forms a piston together with the aluminum alloy.

The 1 and 2 each illustrate, in a roughly schematic longitudinal section, the method according to the invention for producing a cast component 6 in the form of a cylinder block. The 1 shows an insert 1 in the form of a cylinder liner, which has a lateral surface 3 having insert body, which in the example scenario of 1 and 2 as a socket body 2 referred to as. The socket body 2 can be like in 1 be shown sleeve-shaped. Before the socket body 2 in one - in the 1 not shown - mold is introduced, the lateral surface thereof 3 with a layer of silicon oxide, hereinafter "adapter layer" 4 called, coated.

The attachment of such an adapter layer 4 takes place according to a first variant in two process steps: In a first step, a silicone resin is applied to the areas of the lateral surface to be cast 3 applied. In a second step, the silicone resin is heated by heating the socket body 2 cured to silica. For conversion of the organic silicone resin in silica, the socket body 2 For example, be heated by means of a suitable furnace to a temperature of 400 ° C or more. In general, a small layer thickness promotes a rapid curing process, which has an advantageous effect on the industrial production of the cylinder liner in large quantities. Particularly good results in the oxidation of the silicone resin are achieved, if that on the lateral surface 3 applied silicone resin before curing to silicon oxide has a layer thickness of 5 to 10 microns. For this purpose, the silicone resin before application to the lateral surface 3 be diluted by means of a solvent.

According to a second alternative to the first variant, the application of the adapter layer 4 by immersing the cylinder liner in a solution of water glass. The term "water glass" includes all water-soluble sodium, potassium and silicon silicates which have solidified from a melt, in particular Na ₂ O ₃ Si. These silicates have glassy, so amorphous material properties. After immersing the cylinder liner in such a water glass solution, the cylinder liner is dewatered by heating the cylinder liner, preferably to a temperature of 400 ° C or more, analogously to the first variant described above, so cured, so that predominantly remains silica.

The according to the two variants described above with silica coated cylinder liner can now in a in the 2 schematically shown mold 5 be used. Finally, the cylinder liner is form-fitting with an aluminum alloy 7 encapsulated, which completes the cylinder liner to a cylinder block, said aluminum alloy 7 has a magnesium content of at least 0.3% by weight, preferably at least 0.5% by weight. The on the lateral surface 3 the socket body applied adapter layer 4 made of silica causes the die by means of aluminum die casting into the mold 5 introduced aluminum alloy 7 when encasing the cylinder liner shows improved wetting behavior when the aluminum alloy 7 a magnesium content of at least 0.3% by weight, preferably at least 0.5 % By weight. As a result, a particularly good fit between the cylinder liner and aluminum alloy 7 achieved, which in turn ensures a pronounced heat transfer between these two components. The hardened silicon oxide of the adapter layer can react with the magnesium contained in the aluminum alloy in the region of the interface to the aluminum alloy according to the reaction equation SiO ₂ + 2 Mg -> 2 MgO + Si, whereby the wetting of the surface can be decisively improved.

In the 3 is now - as a further, second application example of the method according to the invention - a cast component produced by means of the method according to the invention 6 ' shown in the form of a piston for an internal combustion engine in a rough-schematic longitudinal section.

The 3 shows one with 1' designated insert in the form of a piston ring carrier, which has a lateral surface 3 having insert body, which in the example scenario of 3 as ring carrier body 2 ' referred to as. Before the ring carrier body 2 ' for recasting with an aluminum alloy 7 ' into one - in 3 not shown - mold is introduced, the lateral surface thereof 3 ' with a layer of silicon oxide, hereinafter analogous to the example of 1 and 2 "Adapter layer" 4 called, coated.

For attaching the adapter layer 4 ' mutatis mutandis, the above explanations apply to the example scenario of 1 and 2 That is, for producing a piston according to a first variant, first a silicone resin is applied to the regions of the lateral surface to be cast 3 ' and then heating the ring carrier body 2 ' oxidized to silica. According to a second, the application of the adapter layer takes place 4 ' by immersing the piston ring carrier in a solution of water glass. After immersing the piston ring carrier in such a water glass solution, this is in turn cured by heating the piston ring carrier to silica.

The coated according to the two variants with silica coated piston ring carrier is then inserted into a suitable mold and in this form-fitting with an aluminum alloy 7 ' cast around the piston ring carrier 1' then completed to the piston, said aluminum alloy 7 ' has a magnesium content of at least 0.3% by weight, preferably at least 0.5% by weight. The on the lateral surface 3 of the ring carrier body 2 ' applied adapter layer 4 ' from silicon oxide causes in an analogous manner, for example, the 1 and 2 in that the aluminum alloy introduced into the casting mold by means of aluminum die casting 7 ' when encasing the piston ring carrier shows an improved wetting behavior when the aluminum alloy 7 ' has a magnesium content of at least 0.3% by weight, preferably at least 0.5% by weight. As a result, a particularly good form fit piston ring carrier and aluminum alloy 7 ' achieved, which in turn ensures a pronounced heat transfer between these two components.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 4273835 [0004]
• JP 2010-156003 A [0005]

Claims (12)

Method for producing a cast component ( 6 ; 6 ' ) with an insert ( 1 ; 1' ), comprising the following steps: a) providing an insert ( 1 ; 1' ) with a lateral surface ( 3 ; 3 ' ) insert body ( 2 ; 2 ' ), b) coating the lateral surface ( 3 ; 3 ' ) with an adapter layer ( 4 ; 4 ' ) of silicon oxide, c) arranging the insert ( 1 ; 1' ) in a casting mold, d) positive encapsulation of the insert ( 1 ; 1' ) and the adapter layer ( 4 ; 4 ' ) with an aluminum alloy ( 7 ; 7 ' ) for the production of the cast component ( 6 ; 6 ' ), the aluminum alloy ( 7 ; 7 ' ) has a magnesium content of at least 0.3% by weight, preferably of at least 0.5% by weight. Method according to claim 1, characterized in that - the insert part ( 1 ) a cylinder liner and the molded component ( 6 ) is a cylinder block for an internal combustion engine, or that - the insert ( 1' ) a piston ring carrier and the cast component ( 6 ' ) is a piston for an internal combustion engine. A method according to claim 1 or 2, characterized in that the method step b) comprises the following substeps b1) and b2): b1) applying a silicone resin to the lateral surface ( 3 ; 3 ' b2) curing the silicone resin to silicon oxide by heating the insert body ( 2 ; 2 ' ). A method according to claim 3, characterized in that the silicone resin prior to curing to silicon oxide according to step b2) has a layer thickness of 5 .mu.m to 10 .mu.m. A method according to claim 3 or 4, characterized in that the silicone resin before application to the lateral surface ( 3 ; 3 ' ) is diluted according to step b1) with a solvent. A method according to claim 1 or 2, characterized in that the step b) comprises the following sub-steps b1) and b2): b1) immersion of the insert body ( 2 ) in a solution of water glass, b2) hardening of the water glass to silicon oxide by heating the insert body ( 2 ). A method according to claim 6, characterized in that the water glass comprises Na ₂ O ₃ Si. Method according to one of claims 3 to 6, characterized in that the insert body ( 2 ; 2 ' ) in step b2) is heated to a temperature of 400 ° C or higher. Cylinder liner, in particular produced according to the method according to one of claims 2 to 8, having a jacket surface ( 3 ) having socket body ( 2 ), wherein the lateral surface ( 3 ) of the socket body ( 2 ) with an adapter layer ( 4 ) is coated of silicon oxide. Cylinder block, in particular produced by means of the method according to one of claims 2 to 8, - having at least one cylinder liner according to claim 9, - with an adapter layer ( 4 ) enclosing aluminum alloy ( 7 ), which completes the cylinder liner to the cylinder block. Piston ring carrier, in particular produced according to the method according to one of claims 2 to 8, having a lateral surface ( 3 ' ) having annular body ( 2 ' ), wherein the lateral surface ( 3 ' ) of the ring body ( 2 ' ) at least partially with an adapter layer ( 4 ' ) is coated of silicon oxide. Piston for an internal combustion engine, in particular produced by means of the method according to one of claims 2 to 8, - with at least one piston ring carrier according to claim 11, - with an adapter layer ( 4 ' ) enclosing aluminum alloy ( 7 ' ), which completes the piston ring carrier to the piston.

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